2018-10-22_REVISION - M2008078 (14)

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backfill shall be compacted to a minimum of 90% of the standard proctor maximum dry density for the material used for the backfill. The stabilization rock should have a minimum diameter of 3 inches and be either cobbles or rock excavated from the pit. The stabilization rock should be placed a minimum of 12 inches thick, extend from the bottom of the ditch to the top of the crossing road, and extend a minimum of 10 feet along the ditch bottom and banks from the entrance and exit of the culvert. The access road on the site is gravel surfaced and will be maintained to ensure that tracking of sediment does not extend onto County Road HH.5. The distance between the pit and County Road HH.5, and the gravel surfacing of the access roadway are sufficient to keep sediment from being tracked onto County Road HH.5. D. Identification of Discharges Other Than Stormwater Flows from all disturbed areas will be routed to the sediment ponds in the pit or allowed to infiltrate into the ground without discharging offsite, and will be routed through the BMPs to mitigate any affect they may have on the stormwater quality as it is discharged from the site. The main BMPs will be the sediment settling ponds at the locations discussed above and sediment control logs employed as necessary to limit sediment transport. The sediment ponds will also collect any non-stormwater process water from the washing/screening/crushing facilities to allow sediment to settle from it prior to being discharged, and serve as a pit dewatering point for any non-stormwater groundwater flows that enter the pit. 4. FINAL STABILIZATION AND LONG TERM STORMWATER QUALITY The final stabilization measures will include permanent seeding of all disturbed areas that are above the normal full operating level of the reclaimed water storage reservoir and not part of an access road or structure. The temporary measures such as the sediment control logs within the project site will be removed when the grass seed has germinated and vegetation has reached 70% of pre-disturbance levels. 5. INSPECTION AND MAINTENANCE PROCEDURES The BMP's shall be maintained and kept in good repair for the duration of each phase of the project until final stabilization. PAO shall inspect BMP's weekly and immediately after any significant (greater than 0.1" precipitation) storm events that has caused surface erosion. More frequent inspections may be required to ensure the BMPs are performing acceptably. The maintenance and repair shall be completed in a timely manner. Sediment and debris shall be removed when reaching half of the BMP height or impact the function of the BMP. Areas that are eroded on the pit side slopes shall be re-graded using a dozer or similar type machine to repair the slopes during the mining of the pit. 5